Comments on How To Install MariaDB Galera Cluster on Ubuntu 16.04

Hi, I followed the tutorial but when I execute the command "galera_new_cluster" it says:

galera_new_cluster: command not found

any Idea ?

I am following this tutorial to install Galera on Mariadb 10.3.5 and I get the following error:

"mariadb.service - MariaDB 10.3.5 database server   Loaded: loaded (/lib/systemd/system/mariadb.service; enabled; vendor preset: enabled)  Drop-In: /etc/systemd/system/mariadb.service.d           ??migrated-from-my.cnf-settings.conf   Active: failed (Result: exit-code) since Sun 2018-03-18 18:32:57 +08; 11s ago     Docs: man:mysqld(8)           https://mariadb.com/kb/en/library/systemd/  Process: 2567 ExecStartPost=/bin/sh -c systemctl unset-environment _WSREP_START_POSITION (code=exited, status=0/SUCCESS)  Process: 2562 ExecStartPost=/etc/mysql/debian-start (code=exited, status=0/SUCCESS)  Process: 1714 ExecStart=/usr/sbin/mysqld $MYSQLD_OPTS $_WSREP_NEW_CLUSTER $_WSREP_START_POSITION (code=exited, status=0/SUCCESS)  Process: 4426 ExecStartPre=/bin/sh -c [ ! -e /usr/bin/galera_recovery ] && VAR= ||   VAR=`/usr/bin/galera_recovery`; [ $? -eq 0 ]   && systemctl set-environment _WSREP_START_POSITION=$VAR || exit 1 (code=exited, status=1/FAILURE)  Process: 4408 ExecStartPre=/bin/sh -c systemctl unset-environment _WSREP_START_POSITION (code=exited, status=0/SUCCESS)  Process: 4397 ExecStartPre=/usr/bin/install -m 755 -o mysql -g root -d /var/run/mysqld (code=exited, status=0/SUCCESS) Main PID: 1714 (code=exited, status=0/SUCCESS)Mar 18 18:32:55 gsb-mint systemd[1]: Starting MariaDB 10.3.5 database server...Mar 18 18:32:57 gsb-mint mysqld[4426]: WSREP: Failed to start mysqld for wsrep recovery: '2018-03-18 18:32:55 0 [Note] /usr/sbin/mysqld (mysqld 10.3.5-MariaDB-10.3.5+maria~xenial-log) starting as process 4623 ...Mar 18 18:32:57 gsb-mint mysqld[4426]: 2018-03-18 18:32:55 0 [Note] InnoDB: For Galera, using innodb_lock_schedule_algorithm=fcfsMar 18 18:32:57 gsb-mint mysqld[4426]: 2018-03-18 18:32:55 0 [Note] InnoDB: Mutexes and rw_locks use GCC atomic builtinsMar 18 18:32:57 gsb-mint mysqld[4426]: 2018-03-18 18:32:55 0 [Note] InnoDB: Uses event mutexesMar 18 18:32:57 gsb-mint systemd[1]: mariadb.service: Control process exited, code=exited status=1Mar 18 18:32:57 gsb-mint systemd[1]: Failed to start MariaDB 10.3.5 database server.Mar 18 18:32:57 gsb-mint systemd[1]: mariadb.service: Unit entered failed state.Mar 18 18:32:57 gsb-mint systemd[1]: mariadb.service: Failed with result 'exit-code'." after running the "sudo galera_new_cluster" command.

If I comment all of the lines in the galera.cnf file Mariadb starts normally.

Any idea why the galera.cnf file causes Mariadb to not boot or create mysqld.sock file?

Thanks.

This tutorial works great, on a otherwise clean, fresh installation of Ubuntu 16.04. Great tutorial. Thanks!

Why is rsync needed to be installed?

I cannot see, that you are doing something with it.

Is it used by the galera framework in background?

rsync is used by galera, you can see it in the config:

Hello,

is it possible to have a cluster of 4 galera nodes or the max is 3 nodes?

You can have a cluster of size up to 128 nodes. It's probably advisable to stick to odd numbers - 3, 5, etc - for quorum reasons.